Method and device for controllling the geometry of the chassis of a chain or belt driven vehicle

ABSTRACT

According to the invention, in order to control the vehicle geometry of a chain or belt driven vehicle, chain alignment of the secondary drive is determined by means of a laser module ( 1 ) which is placed on the lateral surface of the chain wheel or the belt pulley and whose the laser beam is directed to the edge area of the chain or belt. Wheel alignment can also be determined, by arranging two pairs of circular segment shaped calibres ( 11 ), which are pressed flat against each other by pressing means ( 12 ) on each side of the rim of at least one back wheel and on at least one front wheel of the vehicle, and by emitting parallel laser beams ( 17 ) on both sides of one of the calibre pairs to the other calibre pair ( 17 ), the laser beams impacting measuring devices ( 13 ) which are arranged on both sides of the other pair of calibres. The dimensional accuracy of the swing and the front wheel fork can also be determined in a similar manner.

The invention relates to a method and a device for checking the chassisgeometry of a chain-driven or belt-driven vehicle.

In many areas, particularly in the case of bicycles and motorcycles, achange in position of the chain wheel sometimes occurs, for example dueto mechanical stresses, maintenance work, tire changes, or changes ofthe secondary drive parts. Because of the slanting of the chain wheelrelative to the belt or the chain that occurs as a result, irregular andgreater wear occurs than in the case of correct alignment. The same isalso true for other belt drives or chain drives, for example in the caseof machinery.

It is known, as the state of the art, to check the alignment of belt orchain with the belt pulley or with the chain wheel, respectively, bymeans of strings or featheredges, but this is both time-consuming andinaccurate.

Furthermore, it is known to provide markings at the axle accommodationof motorcycles. However, these are not very reliable, since even aslightly incorrect position results in errors of several millimetersover the length of the chain. There is hardly any possibility ofchecking the adjustment, except with expensive measurement methods thatare hardly suitable for routine inspections in workshop operations.

A device for checking the chain alignment in motorcycles is known, inwhich a laser is disposed under the vehicle, on a slide rail that isattached at the center of motion of the swing arm. Templates are affixedto the rear wheel, on the sides, at which the laser beam is directed. Inthis device, however, it proves to be disadvantageous that placement canonly be accomplished with a motorcycle jack and with significant effort.Furthermore, the templates are placed against the tire rubber, on thesides, which results in a relatively great measurement error. Finally,the device is relatively expensive.

In the case of the device described above, the two templates areconnected by way of a rod that can be fixed in place, which must bepassed through the wheel, past the rim well. In the case of a diskwheel, this is not possible, and therefore this device cannot be put inplace in the case of a closed carrier between the rim well and the wheelaxle.

A device and a method for aligning at least one alignable plane withregard to at least one reference plane are known from DE 199 83 717 T1.This device particularly serves to align a driving wheel relative to adriven wheel, or vice versa, and has a main part, a light source, and anumber of contact points, whereby the light source is configured to emita laser beam in a plane, at a scattering angle. This device, too, isrelatively complicated, and in many cases requires the time-consumingremoval of protective devices from at least one of the wheels of thebelt drive or chain drive, e.g. the removal of a protective plate or achain guard.

Likewise, a device for aligning belt pulleys by means of laser beams isknown from DE 100 25 918 A1, in which a laser beam transmitter is placedagainst a face of a first pulley and a flat beam emitted by this lasertransmitter falls on targets that are laid against the face of thesecond belt pulley. DE 199 14 300 A1 also describes an alignmentmeasurement device for belt pulleys disposed with parallel axes, inwhich the work is also carried out using targets disposed on the face ofthe belt pulley. However, in many cases, particularly in the case oftwo-wheelers, the second belt pulley is only accessible with difficulty,so that this device can only be used after the second belt pulley hasbeen exposed.

Furthermore, a measurement device for aligning belt pulleys is knownfrom DE 198 38 172 A1, in which a laser is disposed on one of the beltpulleys when the belt has been removed, and is directed at the centerrib of the other belt pulley. However, this is only possible when thebelt has been removed, and this restricts the use of this measurementdevice to an extraordinary degree. In the case of motorcycles with aswing arm rear suspension, the center of motion of the swing arm liesbetween the chain wheel of the rear wheel and the engine pinion.Therefore the view of the pinion is covered.

In the case of the chassis geometry of a chain-driven or belt-drivenvehicle, particularly in the case of bicycles, motorcycles, motorcycleswith side cars, trikes and ATV quads, not only is the arrangement of thetwo chain wheels or belt pulleys relative to one another significant,but also the track of the vehicle, which has a massive influence on thebehavior in curves, for example. Because of design constraints andseries variations in mass production, a track offset to a non-slightdegree can be present in the case of motorcycles produced in largeseries. A track offset of 0 mm is optimal in the case of single-trackvehicles. In practice, the general opinion is that a tolerance of up to2 mm is defensible. An overly great track offset can have a negativeeffect on the handling ability, the steering ability (handlebar out oftrue), straight running, and the steering precision. The simplest methodfor correcting track offset is to distance the rear wheel out in theswing arm, whereby the position of the chain wheel is not allowed to bechanged at correct alignment to the drive pinion.

It is therefore known, from U.S. 2002/0088128 A1, to place devices onthe side, onto the tires of a motorcycle, one of which carries laserarrays on the side, and the other of which carries measurement arraysonto which the laser beams fall. However, it is a disadvantage of thisdevice that because of the unevenness and the elasticity of the tires,the devices are very difficult to align parallel with one another, sothat no parallel laser beams can be sent from one tire to the other.This solution is therefore unsuitable because of the great inaccuracy ofthe measurement.

The invention is therefore based on the task of creating a method and adevice with which the chassis geometry of a chain-driven or belt-drivenvehicle can easily and quickly be checked.

This task is accomplished, according to the invention, by means of amethod for checking the chassis geometry of a chain-driven orbelt-driven vehicle, which has the following method steps:

-   -   Determining the chain alignment of the secondary drive by means        of a laser module that is placed on the lateral surface of the        chain wheel or belt pulley, and whose laser beam is directed at        the edge region of the chain or the belt, respectively.

Here, the flat outside region is placed against the flat lateral surfaceof the belt pulley or the chain wheel, so that the laser beam isdirected at the edge region of the belt or the chain, respectively.Then, in the case of proper belt or chain alignment, a number of laserpoints results on the edge region of the belt or the chain, over anextended distance, with the distance from the edge remaining the same.If this is not the case, a frame/swing arm offset exists, as it occursafter accidents, for example. The device is both very small and veryrobust, and is suitable both for inspections on the road (e.g. after atire change or after a breakdown) and for routine inspections in theworkshop sector. This method of procedure has the advantage that it cantake place without disassembly of parts, because the belt pulley or thechain wheel of the rear wheel and the chain are accessible at least tothe extent required for the inspection. In the case of the pinion, thisis frequently not true. Particularly in the case of motorcycles, thedrive pinions are always covered, partly also by engine block parts, therear wheel swing arm suspension, or frame parts, so that exposure of thedrive pinion is very complicated.

It lies within the framework of the invention that any incorrect chainalignment that is found is subsequently corrected.

If it is not possible to adjust the chain alignment precisely andthereby to set the rear wheel axle at a 90° position relative to thelongitudinal axis of the vehicle, there is a problem in the chassisgeometry. Therefore chassis defects can be recognized, and their causecan actually be determined.

A further development of the invention consists in the followingadditional method step, which takes place before or after the firstmethod step:

-   -   Determining the wheel alignment of the vehicle, in that two        pairs of arc-shaped gages, which are pressed flat against one        another by way of contact pressure means, are disposed on both        sides on the rim of at least one rear wheel and at least one        front wheel of the vehicle, and on both sides, parallel laser        beams are transmitted from one pair of gages to the other pair        of gages, which beams impact the measurement devices disposed on        both sides on the other pair of gages.

The arc-shaped gages are placed against the rim edges of a rear wheeland a front wheel, on both sides, in each instance, which wheels offer asufficiently large, smooth, and easily accessible placement surface. Bymeans of the contact pressure means, the gages are pressed against therims, so that they are disposed parallel to one another, thereby alsocausing the laser beams to run parallel to one another.

In this manner, the track of the vehicle can be checked quickly andprecisely, so that deformations of the fork, for example, resulting froman accident can be easily detected. Likewise, in this manner, the trackcan be checked during assembly or maintenance of the vehicle, with asubsequent adjustment of the track.

This can, of course, also be used in the construction of so-calledcustom bikes, whereby the position of the engine/gear unit, the chainpath, and the wheel axle position must be determined first. Likewise,this method of procedure is also suitable for so-called trikes, and formotorcycles with a sidecar, whereby the laser module or the measurementdevices can be lengthened as needed.

Another further development of the invention consists in the fact thatthe following method step takes place:

-   -   Determining the dimensional stability of the swing arm by means        of two laser modules, which are disposed on both sides of the        hollow axle of a wheel, and whose laser beam is directed at        rulers disposed on both sides, at the center of motion of the        swing arm.

The region of the swing arm mounting on the vehicle frame is one of thelow-torsion regions of the vehicle. The region of the rear wheel axle isdesigned more for torsion, but should be dimensionally stable in thestatic state. This dimensional stability can be checked in that thelaser modules are disposed on both sides in the opening of the hollowaxle of a wheel, preferably by means of cones and centering units, and alaser beam is directed at self-centering rulers that are disposed at thecenter of motion of the swing arm. In this manner, it can be read off onthe ruler whether the axles are located in the same plane.

Another further development of the invention consists in the followingadditional method step, which takes place before or after the firstmethod step:

-   -   Determining the dimensional stability of the front wheel fork,        in that a pair of arc-shaped gages, which are pressed flat        against one another by way of contact pressure means, are        disposed on both sides on the rim of the front wheel of the        vehicle, and laser beams are transmitted on both sides of the        pair of gages, along the fork crosspiece, which beams impact on        measurement devices disposed along the fork crosspiece.

In this manner, it can be determined, for example, whether and whatregion of the relatively sensitive front wheel fork is deformed.

In the case of a device for implementing the method according to theinvention, it is provided that the device consists of at least two pairsof arc-shaped gages that can be pressed flat against one another by wayof contact pressure means, and are configured to rest against the rim ofat least one rear wheel and at least one front wheel of the vehicle, onboth sides, whereby laser modules are disposed on both sides of thefirst pair of gages, with which parallel laser beams can be emitted, andmeasurement devices are disposed on both sides of the second pair ofgages, which are impacted by the laser beams.

Furthermore, it is advantageous that the laser modules can be pivotedabout an axis that stands perpendicular to the arc-shaped gage, in eachinstance, and/or that beams can be emitted by the laser modules in ahorizontal plane.

According to the invention, it is provided that the contact pressuremeans are configured as spring-elastic stirrups that connect the gagesof a pair of gages with one another, around the wheel, in each instance.

An advantageous embodiment of the invention consists in the fact thatthe stirrups are configured to be approximately triangular in shape.

These therefore extend around the wheel of the vehicle, in eachinstance, and nevertheless exert a sufficient contact pressure.

Likewise, it is practical that the measurement devices are configured asrulers that can be inserted into bores in the gages.

In the following, exemplary embodiments of the invention will bedescribed using drawings.

These show:

FIG. 1 a and

FIG. 1 b two exemplary embodiments of a device according to theinvention,

FIGS. 2 a and 2 b inspection of the chain alignment using the twodevices according to FIG. 1 a and FIG. 1 b,

FIG. 3 an ancillary means as a reference part for checking the beltalignment,

FIG. 4 inspection of the belt alignment using the device according toFIG. 1 b and the angled rail according to FIG. 3,

FIG. 5 the arc-shaped gages to be placed against the rims,

FIG. 6 the use of the gages according to FIG. 5 to check the track,

FIG. 7 an additional inspection of the front wheel fork,

FIG. 8 the case configurations in the inspection according to FIG. 7.

As is evident from FIGS. 1 a and 1 b, the device for checking the chainalignment consists of a housing 1 having a flat outside region 2, whichserves as the contact surface. A laser module is disposed in the housing1, in such a manner that a laser beam that is disposed parallel to theflat outside region, which exits from the housing 1 at the exit point 3,can be generated. The laser can be a point laser or a line laser.

In order to be able to operate the device in wireless manner, it ispractical if a power supply (e.g. a battery) for the laser module isdisposed on the housing 1. Furthermore, the housing is preferablyprovided with an activation switch for the laser module as well as (FIG.1 b) with a handle part 4. From FIG. 1 b it is furthermore evident thata notch (K) is provided at an angle of 90° to the flat outside region 2,on the side lying opposite the exit point, which can be laid against theteeth of a belt drive, in order to check the alignment. Alternatively, awedge-shaped contact possibility can also be provided, instead of thenotch (K).

In the case of chain drives, the housing 1 is placed against the face ofthe chain wheel 5 with its flat outside region, to check the chainalignment (FIG. 2 a, 2 b). Since the laser beam generated by the lasermodule is spaced as far apart from the flat outside region as the edgeregion of the chain 6 is spaced apart from the lateral surface of thechain wheel 5, the laser beam runs along the edge region 7 of the chain6 in the case of correct chain alignment. It is also possible that thelaser beam runs parallel to the chain 6. If the chain alignment isinsufficient, it can easily be determined that the laser beam runs awayfrom the edge region of the chain 6.

When checking the alignment of belt drives, there is the problem thatthe belt 8 is usually set back relative to the belt pulley 9 (FIG. 4).For this reason, an elongated angled profile 10, for example (or adifferent reference object) is used, which is laid against an edge ofthe belt 8 and whose parallel measurement lines can then serve to checkthe alignment of the belt.

Alternatively, it can also be provided that the housing 1 of the device,in the front region, is also offset relative to the flat outside region,so that the flat outside region is laid against the outer side of thebelt pulley 9 and the laser beam is directed at the belt 8 in thedirection of its progression.

FIG. 5 shows a top view of one of the arc-shaped gages 11, which is laidagainst the rim or against the rim edge of the vehicle. The device canhave a length of approximately 30 cm, for example, so that a largecontact area is formed. Two of these gages 11, in each instance, arepressed together by means of a contact pressure means 12 in the form ofa spring-elastic stirrup 12, so that they come to rest, parallel, on therim. In order to achieve a good introduction of force, thespring-elastic stirrup 12 is configured to be approximately triangular.One of the pair of gages 11 is provided with a laser module on bothsides, which emits a laser beam, parallel to the longitudinal vehicleaxis 15, which beam impacts a measurement device 13 in the form ofmeasurement rulers 13 that are inserted into the other gage and extendperpendicular to it. If the same distance is found on both sides, thereis no track offset; if the distance is not the same, there is trackoffset.

Finally, FIG. 6 shows how the device according to the invention can beused for checking the track of a motorcycle. For this purpose, thearc-shaped gages 11 are placed against the lateral edges of the rims onboth sides of every wheel, and attached in this position, e.g. by way ofthe spring clips 12 shown, which extend around the running surface ofthe wheel from one side to the other side of the wheel. The devicesaccording to the invention are attached to the gages 11 of the onewheel, in each instance, or at least laid against the wheel with theflat outside region, so that one laser beam, in each instance, isemitted parallel to the longitudinal axis of the motorcycle all the wayto the gages 11 disposed on the other wheel, having measurement rulers13 that project perpendicular away from them. It can then be read on themeasurement rulers 13 whether the same distance is present on bothsides.

Furthermore, a laser beam 17 can also be directed by two laser modules16 on the gages 11 disposed on the rim 22 of the front wheel, on bothsides along the fork crosspiece 18, at measurement rulers disposed onthe latter, and furthermore up to the upper fork bridge 19, 20 to thesteering shaft 21, i.e. the steering head of the frame, as shown in FIG.7. In this connection, it is possible that the laser module 16 is anintegral part of the measurement rulers 13 disposed on the gages 11.

FIG. 8 shows different case configurations in a front view of the frontwheel fork, and the conclusions to be drawn from them, during such aninspection of the front wheel fork.

In the case of FIG. 8 a, the regions A and B are parallel to thecenterline of the vehicle, and the front wheel is disposed parallel tothe center axis of the vehicle (the same values are determined on allmeasurement rulers, in each instance, on the right and on the left).Therefore the front wheel, the fork, and the steering head pipe of theframe are disposed precisely on the centerline of the vehicle. The trackof the vehicle is correct.

In FIG. 8 b, the region A is disposed parallel to the centerline of thevehicle, the front wheel and the region B are not. The track istherefore not correct. The steering head pipe is aligned parallel to thecenterline of the vehicle, and therefore not distorted relative to theframe. However, the fork region B below the lower fork bridge isdamaged.

In FIG. 8 c, neither the region A nor the region B nor the front wheelis disposed parallel to the centerline of the vehicle. In this case, thesteering head pipe (steering head) is distorted relative to the vehicleframe. The fork regions A and B are undamaged.

1. Method for checking the chassis geometry of a chain-driven orbelt-driven vehicle, characterized by the following method step:Determining the chain alignment of the secondary drive by means of alaser module that is placed on the lateral surface of the chain wheel orbelt pulley, and whose laser beam is directed at the edge region of thechain or the belt, respectively.
 2. Method according to claim 1,characterized in that subsequently, any incorrect chain alignment thatis found is corrected.
 3. Method according to claim 1, characterized bythe following additional method step, which takes place before or afterthe first method step: Determining the wheel alignment of the vehicle,in that two pairs of arc-shaped gages, which are pressed flat againstone another by way of contact pressure means, are disposed on both sideson the rim of at least one rear wheel and at least one front wheel ofthe vehicle, and on both sides, parallel laser beams are transmittedfrom one pair of gages to the other pair of gages, which beams impactthe measurement devices disposed on both sides on the other pair ofgages.
 4. Method according to claim 1, characterized by the followingadditional method step, which takes place before or after the firstmethod step: Determining the dimensional stability of the swing arm bymeans of two laser modules, which are disposed on both sides of thehollow axle of a wheel, and whose laser beam is directed at rulersdisposed on both sides, at the center of motion of the swing arm. 5.Method according to claim 1, characterized by the following additionalmethod step, which takes place before or after the first method step:Determining the dimensional stability of the front wheel fork, in that apair of arc-shaped gages, which are pressed flat against one another byway of contact pressure means, are disposed on both sides on the rim ofthe front wheel of the vehicle, and laser beams are transmitted on bothsides of the pair of gages, along the fork crosspiece, which beamsimpact on measurement devices disposed along the fork crosspiece. 6.Device for implementing the method according to claim 3, characterizedin that the device consists of at least two pairs of arc-shaped gages(11) that can be pressed flat against one another by way of contactpressure means (12), and are configured to rest against the rim (22) ofat least one rear wheel and at least one front wheel of the vehicle, onboth sides, whereby laser modules (14) are disposed on both sides of thefirst pair of gages (11), with which parallel laser beams can beemitted, and measurement devices (13) are disposed on both sides of thesecond pair of gages (11), which are impacted by the laser beams. 7.Device according to claim 6, characterized in that the laser modules(14) can be pivoted about an axis that stands perpendicular to thearc-shaped gage (11), in each instance, and can be locked in place inany desired pivot position and/or that beams can be emitted by the lasermodules (14) in a horizontal plane.
 8. Device according to claim 6,characterized in that the contact pressure means (12) are configured asspring-elastic stirrups (12), which connect the gages (11) of a pair ofgages (11) around the wheel of the vehicle, in each instance.
 9. Deviceaccording to claim 8, characterized in that the stirrups (12) areconfigured to be approximately triangular.
 10. Device according to claim6, characterized in that the measurement devices (13) are configured asrulers that can be inserted into bores of the gages (13).